It has become commonplace to perform complex, lengthy, surgical procedures on human (and to a lesser extent veterinary) nerves and blood vessels that have been damaged as the result of trauma. A significant percentage of these procedures involve anastomosis or reconnection of the nerves and blood vessels. Micro-vascular and micro-neurrhal anastomosis also form the basis of free tissue transfer in which composite tissues are moved from one part of the body to another. The blood supply must be immediately reestablished by micro-vascular anastomosis. In cases where an extremity, such as a foot, hand, etc. has been injured, anastomosis is often accomplished using cutting-edge technology microsurgical procedures. However, it will be appreciated that reconnecting structures, many of which can be as small as 1.0 millimeter in diameter is an acquired skill which must be painstakingly learned and routinely practiced in the laboratory prior to application in actual clinical practice.
In view of the foregoing, courses have been conducted in hospitals and laboratories throughout the world for the purpose of training surgeons to perform microsurgical anastomosis. The vast majority of these courses have used laboratory rats, which are relatively inexpensive and easy to acquire, as models for the practical side of training. More specifically, the rat femoral artery and vein closely approximate the smallest, and therefore the most difficult, anastomosis that would reasonably be attempted under clinical conditions. Similarly, the rat sciatic nerve closely simulates the smallest neural structures which would be reasonably attempted under clinical conditions. More particularly, the rat model provides vessels and nerves of ideal size (approximately 1 mm external diameter) which closely approximate the smallest vessels used for free tissue transfer and also approximate the dimensions of the digital arteries, nerves and veins. The rat model allows for instruction and practice in end-to-end arterial anastomosis, end-to-side arterial anastomosis, venous anastomosis and interpositional vein grafting. In summary, the rat provides a realistic substitute for learning most of the microanastomotic procedures which would normally be performed on humans and animals in clinical reconstructive practice.
While physically ideal for training medical and veterinary professionals to perform microsurgical procedures, the rat is not without its inherent drawbacks and deficiencies. For example, as the result of the activities of animal rights organizations, the use of animals in laboratory experiments and for training has been severely restricted. In some countries, such as England, the Home Office will no longer allow licenses for the use of animals in survival experiments for instruction and as practice subjects for the learning of surgical techniques.
The use of laboratory animals also has additional drawbacks as it requires professional husbandry, expert handling and anesthesia for "successful" living experiments. In many cases the foregoing requires the involvement of a veterinarian. Furthermore, live animals also require facilities for euthanasia and disposal at the conclusion of non-survival procedures. Such facilities are unavailable in most hospitals.
The foregoing combined makes it less attractive to use animals in training procedures unless absolutely necessary. Thus, a number of attempts have been made in order to find an acceptable substitute.
Human placental vessels have been used to train surgeons in the techniques of micro-surgery and although the vessel quality is obviously good, blood circulation is not present. In addition, human placentas are not always easy to obtain and when available, they are difficult to transport and preserve satisfactorily for subsequent use. In some cases, isolated pig vessels have been employed as training simulators for vessel structures. Again, availability, storage, and transportation are difficult and blood circulation is lacking.
Rodent carcasses have also been employed in an attempt to minimize the use of animals by "re-using" the carcasses of laboratory rodents that have been euthanized following another procedure or experiment. Again, training is provided on a less than optimal model due to lack of circulation, vessel walls having variable consistency and mechanical properties as a consequence of post-mortem changes and freezing. In addition, the carcasses must be disposed of under closely regulated conditions.
In response to the above-noted problems associated with animal models in general, various attempts have been made to eliminate animals altogether and to provide other microsurgical training devices. For example, in some instances foliage leaves have been used in an attempt to develop microsurgical skills but realism was lacking. Similarly, parts of latex surgical gloves have been and still are, used for basic microsurgical training. However, being essentially two dimensional, their use is limited to exercises in handling fine suture material and to placing sutures and tying knots. Although these exercises are of fundamental importance in the training cycle, they do not allow the student to progress to devices used in microvascular anastomosis, nor to practice those dimensional actions required in joining together small vessels. Furthermore, the rubber glove material tends to grip small needles in an unnatural way, so that it is not even an ideal material for these basic exercises. Nevertheless, the foregoing is marketed under the tradename PracticePak by the Sharpoint Company and contains a latex membrane, together with a length of silicone tubing.
Another product known as the Lumley practice block is also marketed as a training tool by the Ethicon Suture Company and includes a double, hinged, microvascular clamp attached to a solid base. Into this can be introduced lengths of thin tubing which can be divided and sutured. The tubing utilized has been medical tubing, usually Silastic manufactured by Dow Corning, as might be used for intravenous catheters. However, realism in appearance, structure, and "feel" are lacking as well as any form of circulating fluid.
With the foregoing in mind it is an object of the present invention to provide a microsurgical training apparatus which closely simulates an authentic look and feel under which microsurgical procedures are performed.
Another object of the present invention is to provide a microsurgical training apparatus that eliminates the need for laboratory animals.
A further object of the present invention is to provide a microsurgical training apparatus that is as life-like as possible.
Moreover another object of the present invention is to provide a microsurgical training apparatus that is easily stored without changes in its mechanical properties and wherein disposal may be effected without the creation of additional "medical waste".
A still further object of the present invention is to provide a surgical training apparatus that includes a pulsatile flow similar to that created in a normally operating cardiovascular system.
An additional object of the present invention is to provide a microsurgical training apparatus that is inexpensive.
Yet another object of the present invention is to provide a microsurgical training apparatus that has virtually unlimited availability.